1. Field of the Invention
The present invention relates generally to data storage systems for use with computers and, more particularly, to performance evaluation of data storage systems used with computers.
2. Description of the Related Art
Disk drives are commonly used with computers, including desktop computers, notebook computers and servers, to store data. Over the years disk drives have become more advanced so as to offer greater performance and storage capacity. Manufacturers of disk drives provide data sheets or specifications that detail performance and capacity of their disk drives. However, once manufactured, computer companies may want to examine the performance of the disk drives in more detail or in specific applications.
Conventionally, a computer company would either assume that the disk drives are satisfactory given the manufacturer provided performance guarantees, or they perform their own performance testing of the disk drives. Typical testing by computer companies is table-driven, meaning that a table of manufacturer-specific performance data is needed to evaluate the disk drives. One problem with such testing is that different tables would be needed as different disk drives are tested. Such tables are not always readily available. Further, the need for various different tables is cumbersome to those having to perform the testing. Another problem with such testing is that it is dependent on the table data, which is normally provided by the manufacturer, and thus is not necessarily provided for serious performance testing. Still another problem with such testing is that disk drives typically report hard errors but do not report soft errors (i.e., recovered errors). For example, in reading data, if the disk drive initially has an error (i.e., soft error) but on a re-read is able to recover the data correctly, then no error is reported. However, the performance of the disk drive during such read operation is diminished because additional revolutions are required to re-read the data. Each additional revolution causes a performance penalty on the order of seven (7) milliseconds with today's technology.
Thus, there is a need for improved approaches to test performance of disk drives.